Status and Occurrence of Dusky Thrush (Turdus eunomus) in British Columbia. By Rick Toochin, Don Cecile.

Introduction and Distribution The Dusky Thrush (Turdus eunomus) is a beautiful passerine found throughout Northeast Asia (Brazil 2009). There are two very distinct subspecies which are now split by most authorities, including Clements (Clements et al. 2015). Hopefully this means the AOU could split them in the near future, as currently these two distinct subspecies are lumped together under the name Dusky Thrush (Chesser et al. 2015). For purposes of this article, we will follow Clements et al. (2015) in our treatment of Dusky Thrush and keep Naumann's Thrush (Turdus naumanni) as a separate species.

The Dusky Thrush breeds in high altitudes and latitudes in woodland from taiga to the edges of lowland tundra from north-central to north-eastern Siberia, though Mongolia, northern China, east to Yakutia, Chukotka, the Kamchatka Peninsula, and Sakhalin Island (Brazil 2009). The species migrates south to winter from Japan, South Korea, East and Southern China, south to Myanmar, and is found in scarce numbers in the winter in Taiwan (Brazil 2009, Clements et al. 2015). In Alaska, the Dusky Thrush is a casual spring and fall migrant on the Western Aleutian Islands; it is accidental to St. Lawrence Island and St Paul Island, as well as west to Barrow, Askinuk Mountains north of Hooper Bay, and south to Petersburg and Juneau (West 2008). This species is accidental in British Columbia with a couple of records (Toochin et al. 2014, see Table 1). There is only 1 accepted Washington State record by the Washington Bird Records Committee of an adult from Mt. Vernon at an unusual time of year June 27, 2002 (Wahl et al. 2005, WBRC 2014). There are 2 records for the Yukon: with the first occurring in Whitehorse November 21-28, 2000 (Eckert 2001, Sinclair et al. 2003); and the second found June 28-29, 2003 at Craig Creek in Ivvavik National Park, near the Beaufort Sea (Eckert and McTavish 2004). This species is a casual vagrant to Europe with several records (Lewington et al. 1992).

The Naumann’s Thrush has a much more southerly and eastern breeding and winter range than the Dusky Thrush in Far East Asia (Brazil 2009). The Naumann’s Thrush breeds in lower altitudes and latitudes in woodland from taiga to the edges of lowland tundra in south-central Asia from the Yenisei River to the Lena River in Siberia to northern Manchuria (Brazil 2009, Clements et al. 2015). This species migrates south to winter in Ussuriland, Korea, and parts of eastern and southern China (Brazil 2009, Clements et al. 2015). This species is an accidental vagrant in Europe, and occurs far less frequently than Dusky Thrush (Lewington et al. 1992). In North America, Naumann’s Thrush is an accidental vagrant species known from only a couple of sight records from the Outer Aleutian Islands, in Alaska (Clements et al. 2015).

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Identification and Similar Species The identification of the Dusky Thrush is covered in most standard North American field guides. This species measures 24 cm in length and weighs 55 to 106 grams (Jonsson 1992, Brazil 2009). This makes the Dusky Thrush slightly smaller than an American Robin which measures 25 cm and weighs on average 77 grams (Sibley 2000). The Naumann’s Thrush is a little smaller than the Dusky Thrush measuring 23 cm in length. The separation of Dusky Thrush from the Naumann’s Thrush is tricky, especially since there is a hybridization zone. With careful observation and good photographs, it should be possible to identify a possible Dusky Thrush.

The two species have been separated in the following descriptive account that is taken from Brazil (2009) unless otherwise stated.

Dusky Thrush (Turdus eunomus) The Dusky Thrush is extremely variable, but generally dark with much black on the face and underparts. It has extensively rusty-red in the wings (coverts, primary bases, and tertials) and rump, but none in tail. Much more contrasting than Naumann’s Thrush, though it can be confusingly similar. The adult male has a prominent creamy white supercilium, chin, throat, breast, and neck bar with blackish-brown lores and ear coverts. There is a narrow dark brown lateral throat-stripe, black breast-band and heavy black scaling on the breast and flanks. The crown through to the back is olive-brown: the tail is dark brown. The wings appear mostly bright rufous-brown due to extensive rufous fringing to scapulars, coverts, secondaries and tertials. The adult female is poorly marked and is less heavily marked than the adult male. The female has a dark brown tail, and a distinct rufous wing-panel, albeit less conspicuous than the adult male; and there are some females that lack rufous in the wings. The bill has a blackish tip and culmen with a yellow lower mandible and is brighter than found on Naumann’s Thrush. The eyes are black; the legs are dull brownish-yellow.

First winter birds are similar to adults, but have retained juvenile pale edges and tips to the greater coverts with less rufous-brown on the upper wing (Lewington et al. 1992).

In flight, the tail lacks rufous, but much of the wing appears bright rufous-brown. It also has rufous axillaries.

The Dusky Thrush makes a varied sibilant and chattering “kii-kii”, “chirii”, “tsuii” or “shreee” and also gives a “quwatt-quwatt”as well as a strident “check-check-check-check” and a staccato alarm note “chuck”.

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Naumann’s Thrush (Turdus naumanni) This species is variable, but adults are generally mid grey-brown from the forehead to the upper back, and rusty-red to brick-orange on the lower back to the base and outer tail (which is always lacking in Dusky Thrush). The adult male has a buff or orange face a with brick orange supercilium, neck sides and malar with the throat bordered by grey-brown lateral throat stripes. The underparts are variably rufous-orange white scaling from the lower chest to vent, and a white central belly. The adult females have darker streaking on the throat-sides with little or no rufous-orange on the face and less red on the underparts. The bill has a blackish tip and culmen with a yellow lower mandible. The eyes are dark. The legs are a dull brownish-yellow.

First winter birds have throat streaking extending to the neck-and breast-sides. Birds at this age have retained juvenile pale edges and tips to the greater coverts (Lewington et al. 1992)

In flight, the outer tail feathers are distinctly rufous-orange with the wings showing only limited or no rufous-brown panel on secondaries.

The Naumann’s Thrush makes a shrill or nasal “cheeh”, a harsh “shak” or “chack” when alarmed that is often repeated, sometimes in a series.

It is important to note that hybrids between the 2 species do occur and can show intermediate traits of both species.

Occurrence and Documentation The Dusky Thrush is an accidental vagrant species anywhere in British Columbia. The first record was of an adult bird found by John Ireland while conducting the White Rock Christmas Bird count on January 2, 1993, that stayed until April 9, 1993 at 20015 Fernridge Crescent, Langley, and was subsequently seen and photographed by hundreds of people from all over the world (McKay 1993, Siddle and Bowling 1993, Tyson 1993, Davidson 1994). The Dusky Thrush spent the entire winter in a small stand of Holly Trees with a flock of American Robins (R. Toochin Pers. Comm.). The bird became at home in the Holly Trees and defended these trees as a feeding territory from the American Robins making it easily found the entire period it was in the area (R. Toochin Pers. Comm.). The second record was an immature bird found by Tony Greenfield at Tofino Airport with a flock of American Robins on October 30, 1994 (Bowling 1995a, Toochin et al. 2014). Despite a search the following day, the bird was not relocated. A published account in The Birds of British Columbia Volume 3 has a record of an adult bird found by Mike Gill at the Alasken National Wildlife Refuge on November 22, 1994 (Bowling 1995a, Campbell et al. 1997). This record is deemed a misidentification since a leucistic American Robin was observed at this location the following day (R. Toochin Pers. Comm.).

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The Dusky Thrush winters in South Korea and Japan, which is very close to the same latitude as Langley. Since this species winters at northern latitudes, it is much more likely to occur again in the winter with a flock of American Robins and, therefore, should be watched for by observers in the future. The Dusky Thrush is most likely to occur in the fall from late September to November, the winter months or possibly during the Spring migration with a bird that has wintered somewhere in the New World. The June record for Washington adds a definite twist to our understanding of when it would be logical to look for this species. The Dusky Thrush is regular enough in Alaska that observers everywhere in British Columbia should be on the lookout for this spectacular Asian thrush.

Figure 1: Record #1: Dusky Thrush at 20015 Fernridge Crescent, Langley, January 5, 1993. Photo © Marty Kaplan.

Table 1: Records of Dusky Thrush for British Columbia: 1.(1) adult January 2- April 9, 1993: John Ireland, mobs (photo) 20015 Fernridge Crescent, Langley (McKay 1993, Siddle and Bowling 1993, Tyson 1993, Davidson 1994) 2.(1) immature October 30, 1994: Tony Greenfield: with American Robins, Tofino Airport (Bowling 1995a, Toochin et al. 2014)

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Hypothetical Records: 1.(1) adult November 22, 1994: Mike Gill, mobs: Alasken National Wildlife Refuge (Bowling 1995a, Campbell et al. 1997) [Refound next day and was very likely a leucistic American Robin (R. Toochin Pers. Comm.)

Acknowledgements We wish to thank Marty Kaplan for allowing us the use of his Dusky Thrush image taken in Langley, British Columbia, in January 1993. All photos are used with permission of the photographer and are fully protected by copyright law. These images are not to be retransmitted or used for any purpose without the expressed written consent of the photographer.

References Bowling, J. 1995a. The fall migration – British Columbia/Yukon region. North American Field Notes 49: 87- 92.

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Wahl, T. R., B. Tweit, and S. Mlodinow. 2005. Birds of Washington: Status and Distribution. Oregon State University Press, Corvallis, Oregon. 436pp.

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